An аutomatic mode control of the jet mill loading

Abstract

A thin jet grinding is quite an energy-consuming process. Its production depends on the fullness of the mill chamber with material. Therefore, it is extremely important to control the loading of the jets with material and to reload the necessary portion of material in time.
Previous studies have shown the effectiveness of control the jet grinding process based on acoustic monitoring. The interrelation of technological, regime and acoustic parameters of the process has been established, an automated mill control system is being developed. For each required size of the ready product, its own grinding mode and classification and, accordingly, its range of acoustic signal characteristics are set to achieve maximum grinding productivity. This is the basis for controlling the jet mill operation according to the results of acoustic monitoring.
The aim of the paper is to develop an automated control system for the loading bunker of the jet mill based on the analysis of the acoustic signals of the grinding zone.
The study was conducted for different recording modes of acoustic monitoring signals and the grinding process of various bulk materials. To amplify the signal, an operational amplifier with a gain of 10 was used. To eliminate the measurement error, a sample of 100 values is taken. The used equipment has a limit time for the ADC polling for each program cycle. To estimate the error, an experimental study of signals was carried out. After processing all the data, the control signal is fed to the control unit of the solenoid, which is assembled on the basis of a field-effect transistor with an operating voltage of 60 V and a maximum current is up to 100 A. Then the control signal is transmitted to the opening or closing of the loading bunker gate.
The numerical experiment improved the analyzing method of the acoustic signal of the grinding zone, reduced the error. A hardware base of the control system was created and a model of a controlled loading bunker was implemented. A mill loading control system has been developed through a controlled bunker based on the results of continuous acoustic monitoring of the grinding process.